Prevalence of Leishmania infantum infection in dogs living in an area of canine leishmaniasis endemicity using PCR on several tissues and serology

Performance of a point-of-care test for the detection of anti-Leishmania infantum antibodies is associated with immunofluorescent antibody titer and clinical stage of leishmaniosis in dogs from endemic regions

Canine leishmaniosis (CanL) is caused by the protozoal parasite Leishmania infantum, which is transmitted by sand flies in warm climates across the world. Because dogs are considered a primary domestic reservoir for the parasite that causes leishmaniosis in humans, it is important from a One Health perspective that CanL be properly managed. In endemic regions, CanL is a common differential diagnosis in sick dogs because the clinical signs and clinicopathological disorders of the disease are non-specific, variable, and may overlap those of other common conditions. Diagnosis is based on the presence of compatible clinical signs, laboratory abnormalities, and confirmation by serological and parasitological evidence of infection. Here, we describe the performance of a point-of-care (POC) immunoassay that uses recombinant antigens to detect canine anti- L. infantum antibodies in a convenience sample set from a diagnostic laboratory, a group of canine patients with clinical staging, and in apparently healthy dogs from endemic areas. An immunofluorescence antibody test (IFAT) was used as the semiquantitative reference method. In the convenience sample set with high IFAT titers (≥ 1:800), the POC immunoassay demonstrated perfect agreement with IFAT (100%; 90/90). Using samples from dogs staged as either LeishVet Stage 2 or 3 or LeishVet Stage 1, positive agreement of the POC immunoassay with the IFAT was 98.8% (82/83) and 83.8% (31/37), respectively. The negative agreement with IFAT was 98.9% (272/275) in apparently healthy dogs from endemic areas of Greece and Italy. Since the performance of the POC immunoassay was associated with IFAT titer and clinical stage of CanL, the test may help veterinarians when determining if CanL is likely responsible for a patient's clinical picture or when evaluating an apparently healthy patient prior to vaccination.

Epidemiological surveillance of Leishmania infantum in wild lagomorphs in Spanish Mediterranean ecosystems

Wild lagomorphs play a key epidemiological role as reservoirs of Leishmania infantum, causative agent of the largest outbreak of human leishmaniosis in Europe to date. A large-scale survey study was conducted on wild rabbit (Oryctolagus cuniculus) and Iberian hare (Lepus granatensis) populations in Spanish Mediterranean ecosystems to evaluate the exposure of L. infantum and investigate potential risk factors associated with exposure to this zoonotic parasite. Between 2018 and 2021, a total of 631 wild lagomorphs (471 wild rabbits and 160 Iberian hares) were collected in Andalusia (southern Spain) and tested for antibodies against L. infantum using the indirect fluorescent antibody test (IFAT). Spleen samples from 563 of the wild lagomorphs sampled (441 wild rabbits and 122 Iberian hares) were also evaluated by real-time quantitative PCR (qPCR) for detection of Leishmania kDNA. Exposure to L. infantum (positive by IFAT and/or qPCR) was detected in 56.4 % (356/631; 95 %CI: 52.3-60.3) of the lagomorphs analyzed. Anti-Leishmania antibodies were found in 12.8 % (81/631; 95 %CI: 10.2-15.5) of the animals, and L. infantum kDNA was detected in 59.0 % (332/563; 95 %CI: 54.9-63.0) of the spleen samples tested. Phylogenetic analysis revealed high homology (99.9-100 %) between L. infantum sequences obtained and strains previously isolated from humans in Spain. While apparent seroprevalence was significantly higher in Iberian hares (19.4 %; 95 %CI: 13.3-25.5) compared to wild rabbits (10.6 %; 95 %CI: 7.9-13.4), no significant differences in prevalence were found between wild rabbits (61.0 %; 95 %CI: 56.5-65.6) and Iberian hares (51.6 %; 95 %CI: 42.8-60.5). At least one positive animal was found on 64.8 % (70/108) of the hunting grounds sampled, and a high-risk spatial cluster (P < 0.001) was also identified in central Andalusia. The multivariable analysis identified bioclimatic level (meso-Mediterranean climate) and the presence of goats on hunting grounds as risk factors potentially associated with L. infantum exposure in wild lagomorphs. This study shows high, widespread exposure, but heterogeneous distribution of L. infantum in wild lagomorph populations in Mediterranean ecosystems in southern Spain. The results point to the need to promote integrated surveillance programs for the detection of Leishmania spp. in wild lagomorphs in order to establish effective control measures against human leishmaniosis under a One Health approach.

Global Distribution of Canine Visceral Leishmaniasis and the Role of the Dog in the Epidemiology of the Disease

Visceral leishmaniasis is a disease caused by protozoa of the species Leishmania (Leishmania) infantum (syn = Leishmania chagasi) and Leishmania (Leishmania) donovani, which are transmitted by hematophagous insects of the genera Lutzomyia and Phlebotomus. The domestic dog (Canis familiaris) is considered the main urban reservoir of the parasite due to the high parasite load on its skin, serving as a source of infection for sandfly vectors and, consequently, perpetuating the disease in the urban environment. Some factors are considered important in the perpetuation and spread of canine visceral leishmaniasis (CVL) in urban areas, such as stray dogs, with their errant behavior, and houses that have backyards with trees, shade, and organic materials, creating an attractive environment for sandfly vectors. CVL is found in approximately 50 countries, with the number of infected dogs reaching millions. However, due to the difficulty of controlling and diagnosing the disease, the number of infected animals could be even greater. In the four continents endemic for CVL, there are reports of disease expansion in endemic countries such as Brazil, Italy, Morocco, and Tunisia, as well as in areas where CVL is not endemic, for example, Uruguay. Socio-environmental factors, such as migration, drought, deforestation, and global warming, have been pointed out as reasons for the expansion into areas where it had been absent. Thus, the objective of this review is to address (i) the distribution of CVL in endemic areas, (ii) the role of the dog in the visceral leishmaniasis epidemiology and the factors that influence dog infection and the spread of the disease, and (iii) the challenges faced in the control of CVL.

Alternative hosts of Leishmania infantum: a neglected parasite in Europe

Multi-host pathogens that infect various animal species and humans are considered of great importance for public and animal health. Leishmania spp. parasites are a characteristic example of such pathogens. Although leishmaniosis in humans is endemic for about 100 countries around the world it is classified as a neglected tropical disease. There are three main forms of leishmaniosis in humans: cutaneous (CL), visceral (VL) and mucocutaneous leishmaniosis (MCL). Each year, about 30,000 new cases of VL and more than 1 million new cases of CL are recorded. In Europe L. infantum is the dominant species with dogs being reservoir hosts. Apart from dogs, infection has been recorded in various animals, which suggests that other species could play a role in the maintenance of the parasite in nature. Herein we provide an in-depth review of the literature with respect to studies that deal with Leishmania infantum infections in domestic and wild animal species in Europe. Given the fact that domesticated and wild animals could contribute to the incidences of leishmaniosis in humans, the aim of this paper is to provide a comprehensive review which could potentially be used for the development of measures when it comes to the control of the Leishmania infantum parasite.

[Overview on utility of in-house tests for detection of systemic infectious diseases in dogs]

For detection of infectious diseases, several point-of-care (POC) tests are on the market in addition to methods performed in commercial laboratories. These POC tests are based on enzyme-linked immunosorbent assay (ELISA) or other immunochromatographic technologies and present results within few minutes in veterinary practice. This article gives an overview of the utility of numerous POC tests of different manufacturers for detection of parvovirus antigen in feces, Dirofilaria (D.) immitis antigen in blood as well as antibodies against Borrelia (B.) burgdorferi, Anaplasma (A.) spp., Ehrlichia (E.) spp., Leptospira (L.) spp. and Leishmania (L.) infantum in blood (single or in different combinations). Sensitivity and specificity of these tests are important for their usefulness in veterinary practice. Furthermore, presence of antibodies or detection of antigen has to correlate with the presence of clinical signs. POC tests for detection of canine parvovirus antigen have a very high specificity, the sensitivity of all evaluated POC tests, however, is very low. POC tests for detection of D. immitis antigen have a very high sensitivity and specificity. As they detect antigen from the uterus of female adult parasites, test results are negative when only very few female or only male adults are present. POC tests for detection of antibodies against B. burgdorferi only indicate contact with Borrelia spp. and do not prove clinical Lyme disease, as the infection only extremely rarely causes clinical signs. POC tests for detection of antibodies against A. phagocytophilum are also not suitable for diagnosis of clinical anaplasmosis. Infections with A. phagocytophilum only lead to clinical disease in very rare cases and in these, clinical signs occur before the development of antibodies. POC tests for detection of antibodies against E. canis have a very high sensitivity as well as specificity. POC tests for detection of antibodies against L. infantum and Leptospira species (spp.) show a very high specificity and a high sensitivity. However, Leptospira spp. antibody-positive results may occur following vaccination, as the POC tests cannot distinguish between field and vaccination strains.

Challenges of animals shelters in caring for dogs infected with Leishmania and other pathogens

The incidence of human Visceral Leishmaniasis (VL) has decreased in Brazil; however, the number of areas reporting human and canine cases has increased, with Leishmania infantum usually preceding human infection. This study aimed to analyze the profile of infectious diseases that are endemic for both human and canine VL, in dogs housed in a shelter located in the state of Rio Grande do Norte, Northeast Brazil. Data was obtained between November/2021 to April/2022. All dogs residing at the shelter (98 dogs) were examined and blood was collected for testing for L. infantum, Ehrlichia canis, and Babesia sp. Statistical analyses considered the clinical and laboratory findings. Of the 98 animals, approximately 43% were positive for L. infantum antibodies, 19% were positive for L. infantum kDNA, and 18% were L. infantum positive by culture. Greater levels of anti-leishmania antibodies were observed in dogs with symptoms suggestive of VL. The dogs tested positive for E. canis (19/98) and B. canis (18/98). Lutzomyia longipalpis was captured inside the shelter, representing 74.25% (n = 225) of whole sandflies in the dog shelter. Concomitant infection by L. infantum and E. canis increased the odds of death. Treatment of VL included the use of allopurinol (n = 48) and miltefosine (n = 8). Treated animals showed more signs of Leishmania infection. Tickborn parasites and Leishmania were prevalent in sheltered dogs in a VL-endemic area, which increases the odds of death and poses an additional challenge for caring for abandoned dogs and at the same time setting protocols to manage reservoirs of L. infantum.

Serological survey of Leishmania infantum in apparently healthy dogs in different areas of Spain

BACKGROUND

Canine leishmaniosis caused by Leishmania infantum is an endemic disease in Spain. The dog is considered the main reservoir, and the detection of specific serum antibodies against L. infantum antigen is the most used technique for diagnosing this infection. The LEISCAN LEISHMANIA ELISA test is a commercialized enzyme-linked immunosorbent assay for the detection and measurement of canine anti-Leishmania serum antibodies.

OBJECTIVES

The aim of this study was to assess seroprevalence results of apparently healthy dogs in different areas of Spain using LEISCAN.

METHODS

Collection of sera from 5451 apparently healthy dogs was performed between 2020 and 2021 in different areas of Spain. Dogs were of adult age (≥12 months), were not previously diagnosed with clinical leishmaniosis or vaccinated against Leishmania and did not present clinical signs compatible with L. infantum infection. LEISCAN was performed following the manufacturer's protocol.

RESULTS

The overall seroprevalence was 5.5%. The highest seroprevalences were found in the Southeast of Spain: Comunidad Valenciana (14%) and Región de Murcia (14%), whereas the lowest seroprevalences were found in Northern Spain: Galicia (1%), Navarra (2%) and Castilla y León (2%) (p-value <0.001).

CONCLUSIONS

In conclusion, the seroprevalence for L. infantum in apparently healthy dogs in Spain varied from almost no infection to being over 10%.

Canine Leishmania spp. infection in two distinct foci of visceral and cutaneous leishmaniasis in Tunisia

Visceral leishmaniasis (VL) and zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania (L.) infantum and L. major, respectively, are endemic in Tunisia. The aim of the study was to assess canine Leishmania spp. infection prevalence as well as to identify the Leishmania species involved in two well-documented and geographically distinct VL and ZCL foci. One hundred seventy-six dogs were randomly recruited in the VL focus of Sbikha-Zaghouan (n = 100) and the ZCL focus of Echrarda-Nasrallah (n = 76). Physical examination and blood collection were systemically performed. Needle aspiration was done in case of lymph node (LN) enlargement. All sera were tested by ELISA. kDNA RT-PCR was performed on DNA extracts from (i) buffy coats of seropositive dogs and (ii) LN aspirates. Leishmania species identification was done by ITS1 PCR-sequencing. Thirty-three dogs (18.8%) were infected by Leishmania; 30 having anti-Leishmania antibodies and 3 were seronegative dogs with Leishmania DNA in LN aspirates. Prevalence of infection was significantly higher in VL foci than in ZCL foci (27% versus 7.9%, p = 0.002). Leishmania species was identified in 11 dogs and corresponded to L. infantum. Combination of serology and qPCR on LN aspirates seems to be the best option for canine leishmaniasis diagnosis. Infection is more frequent in VL foci and L. infantum is the only identified species.

Leishmaniosis in Greece: The Veterinary Perspective

Leishmaniosis caused by the protozoon Leishmania infantum that is transmitted through the bites of infected phlebotomine sandflies is of major veterinary concern in Greece. The country is endemic with particularly favourable environmental conditions for the spread of this infection. Moreover, Greece remains a popular touristic destination, and the continuous travel of pets raises concern regarding the possible dissemination of infection from endemic to non-endemic areas. Dogs are the main reservoir host, although other animal species, including humans, may also be infected. Canine leishmaniosis manifests as a visceral disease that can result in death if left untreated. Serological and molecular epizootiological studies have confirmed circulation of the parasite in Greek canine and feline populations as well as in other mammals. As a result, constant surveillance and identification of high-risk localities are necessary to establish chemoprophylactic protocols for travelling animals to safeguard animal and public health.

Animal leishmaniasis in Algeria: A systematic review and meta-analysis

Leishmaniasis is a neglected tropical parasitic vector-borne disease that has emerged or re-emerged in recent years and is a major health problem. Algeria is a country where leishmaniasis reaches high levels of endemicity. This systematic review and meta-analysis was performed to collect, compile and summarise data on the prevalence of animal leishmaniasis in Algeria. Data were collected from 2004 to 2022 during which a number of 12 papers were published from dogs, cats, hedgehogs, and jackals. A total of 4812 dogs, 388 stray cats, 24 hedgehogs and 2 Jackals were included in this analysis. The diagnosis of leishmaniasis was performed using serological or molecular tests. The overall prevalence in dogs was 21.2 % (95 %CI, 15.7-26.9 %), and in stray cats, hedgehogs and Jackal was, respectively, 25.3 % (95 %CI, 17-36.6 %), 20.8 % (95 %CI, 8.8-40.9 %) and 50 %. This study is a comprehensive epidemiological analysis of canine leishmaniasis in Algeria and will therefore be a useful tool for researchers. Further studies are needed for a better and continuous assessment of the occurrence of this zoonosis. It can also be used to propose or improve appropriate national surveillance programs for these diseases.

Wild Mesocarnivores as Reservoirs of Endoparasites Causing Important Zoonoses and Emerging Bridging Infections across Europe

Mesocarnivores are small- or mid-sized carnivore species that display a variety of ecologies and behaviours. In Europe, wild mesocarnivores are represented by the red fox (Vulpes vulpes), the golden jackal (Canis aureus), the European wildcat (Felis silvestris), the Mustelidae of the genera Meles, Martes, Mustela, Lutra, the invasive species of raccoon dog (Nyctereutes procyonoides), raccoons (Procyon lotor), and American mink (Neogale vison). These abundant animals thrive in various habitats and often develop their activity close to human settlements. Thus, they may play an important role in the introduction, maintenance, and transmission of major parasitic zoonoses and promote bridging infections with domestic animals. Against this background, this article reports and discusses some of the most important endoparasites of wild mesocarnivores living in Europe, on the basis of their actual role as reservoirs, spreaders, or sentinels. The data derived from epizootiological studies in different European countries, and the proven or speculated implications of the detected endoparasites in human and domestic animals' health, are discussed. Through older and recent literature review, the state-of-the-art knowledge on the occurrence and prevalence of the parasites under consideration is presented, showing further, warranted investigations and the need for surveillance and vigilance.

Detecting Leishmania in dogs: A hierarchical-modeling approach to investigate the performance of parasitological and qPCR-based diagnostic procedures

BACKGROUND

Domestic dogs are primary reservoir hosts of Leishmania infantum, the agent of visceral leishmaniasis. Detecting dog infections is central to epidemiological inference, disease prevention, and veterinary practice. Error-free diagnostic procedures, however, are lacking, and the performance of those available is difficult to measure in the absence of fail-safe "reference standards". Here, we illustrate how a hierarchical-modeling approach can be used to formally account for false-negative and false-positive results when investigating the process of Leishmania detection in dogs.

METHODS/FINDINGS

We studied 294 field-sampled dogs of unknown infection status from a Leishmania-endemic region. We ran 350 parasitological tests (bone-marrow microscopy and culture) and 1,016 qPCR assays (blood, bone-marrow, and eye-swab samples with amplifiable DNA). Using replicate test results and site-occupancy models, we estimated (a) clinical sensitivity for each diagnostic procedure and (b) clinical specificity for qPCRs; parasitological tests were assumed 100% specific. Initial modeling revealed qPCR specificity < 94%; we tracked the source of this unexpected result to some qPCR plates having subtle signs of possible contamination. Using multi-model inference, we formally accounted for suspected plate contamination and estimated qPCR sensitivity at 49-53% across sample types and dog clinical conditions; qPCR specificity was high (95-96%), but fell to 81-82% for assays run in plates with suspected contamination. The sensitivity of parasitological procedures was low (~12-13%), but increased to ~33% (with substantial uncertainty) for bone-marrow culture in seriously-diseased dogs. Leishmania-infection frequency estimates (~49-50% across clinical conditions) were lower than observed (~60%).

CONCLUSIONS

We provide statistical estimates of key performance parameters for five diagnostic procedures used to detect Leishmania in dogs. Low clinical sensitivies likely reflect the absence of Leishmania parasites/DNA in perhaps ~50-70% of samples drawn from infected dogs. Although qPCR performance was similar across sample types, non-invasive eye-swabs were overall less likely to contain amplifiable DNA. Finally, modeling was instrumental to discovering (and formally accounting for) possible qPCR-plate contamination; even with stringent negative/blank-control scoring, ~4-5% of positive qPCRs were most likely false-positives. This work shows, in sum, how hierarchical site-occupancy models can sharpen our understanding of the problem of diagnosing host infections with hard-to-detect pathogens including Leishmania.

Diagnosis and prevalence of canine leishmaniasis in the Atlas shepherd dog

The aim of this study was to determine the prevalence of canine leishmaniasis in the Atlas shepherd dogs from the Tiaret region of Algeria. A total of 161 dogs were included in this study and four diagnostic techniques were used, namely lymph node cytology, PCR, IFAT and ELISA. 110 out of 161 dogs were positive by at least one diagnostic technique, a percentage of 68.32% of the total number, which represent very high prevalence of canine leishmaniasis in this canine breed. 152 dogs underwent the two serological tests namely IFAT and ELISA among which 137 dogs underwent in addition the molecular examination by PCR. IFAT was positive in 9.86% of the dogs, ELISA was positive in 12.5% while 68% of the dogs proved positive by PCR. 47 dogs with lymph node enlargement underwent lymph node cytology, of which 26 dogs showed forms of amastigotes in their smears after microscopic examination, confirming the usefulness of this approach for the diagnosis of canine leishmaniasis. The clinical signs of the disease in this breed are similar to those of other canine breeds The dominant clinical signs in these dogs were onychogryphosis, poor general condition and lymph node hypertrophy. The autopsy was carried out on 7 dogs that died of canine leishmaniasis, all of which showed splenomegaly, while 5 dogs also showed hepatomegaly. Renal damage was found in 1 dog with frank jaundice. The splenic cytology was positive in all 7 dogs with the presence of amastigote forms in the smears after microscopic examination.

Absence of DNA and anti-leishmanial antibodies in dogs (Canis familiaris) in Plateau state, Nigeria

Dogs are important sentinels for the surveillance of some zoonotic diseases including human leishmaniasis. To obtain information on the role of dogs in the epidemiology of leishmaniasis in Nigeria, 98 sera and 204 DNA samples obtained from dogs were screened for anti-leishmania antibodies and DNA of Leishmania spp. using the enzyme linked immunosorbent assay (ELISA) and PCR, respectively. Initially, three out of the 98 sera samples had ELISA borderline optical density (OD) values and were retested. Two out of the three samples turned out to be negative while one sample gave yet a borderline OD value on a retest. A real time polymerase chain reaction (RT-PCR) targeting the 120-bp fragment of the minicircle kDNA of Leishmania spp. run on DNA extracted from EDTA preserved blood of the borderline positive serum failed to amplify the 120-bp sequence of Leishmania spp. In the second phase of the study, 204 DNA from dog blood samples were subjected to conventional PCR targeting the 300-350 bp of the internal transcribe spacer region 1 (ITS1) of Leishmania spp. None of the samples could be amplified (n = 204, 0%). Our study suggests that L. infantum is not prevalence in Jos, Plateau State, Nigeria and this should be confirmed using a larger sample of local dogs tested using PCR methods in lymphoid tissue samples.

Review and statistical analysis of clinical management of feline leishmaniosis caused by Leishmania infantum

Background

There is limited information about feline leishmaniosis (FeL) management in clinical practice. Leishmania infantum is the species of Leishmania most frequently reported in both dogs and cats in countries of the Mediterranean region (henceforth ‘Mediterranean countries’), Central and South America, and Iran. This study was conducted to provide veterinary clinicians with an updated overview of evidence-based information on leishmaniosis in cats.

Methods

A review was performed using PubMed, Science Direct, Google Scholar and Web of Science. Case reports of FeL caused by L. infantum were sought for the period 1912 to 1 June 2021.

Results

Sixty-three case reports are included in this review. Fifty-nine out of the 63 cats were from Europe, mostly from Mediterranean countries (88.9%). Most of them were domestic short-haired cats (90%) with a mean age of 7.9 years, and had access to the outdoors (77.3%). Sixty-six percent of the cats had comorbidities, of which feline immunodeficiency virus infection was the most frequent (37.7%). Dermatological lesions (69.8%) was the most frequent clinical sign, and hyperproteinemia (46.3%) the most frequent clinicopathological abnormality. Serology was the most performed diagnostic method (76.2%) and was positive for 93.7% of cats. Medical treatment was applied in 71.4% of cats, and allopurinol was the most used drug (74.4%). Survival time was greater for treated cats (520 days; 71.4% of cats) than non-treated cats (210 days; 25.4%).

Conclusions

The majority of the cats had comorbidities, of which feline immunodeficiency virus was the most frequent. Dermatological lesions were frequently reported, and systemic clinical signs and clinicopathological abnormalities were also common. Serology may be useful for the diagnosis of FeL in clinical practice, and a positive titer of ≥ 1/40 may be a useful cut-off for sick cats. The reported treatments and dosages varied, but there was a good clinical response and longer survival in most of the cats treated with allopurinol monotherapy.

Graphical abstract

A mixed-methods approach to understanding domestic dog health and disease transmission risk in an indigenous reserve in Guyana, South America

Domestic dogs (Canis lupus familiaris) can transmit a variety of pathogens due to their ubiquitousness in urban, rural and natural environments, and their close interactions with wildlife and humans. In this study, we used a mixed-methods approach to assess the role of domestic dogs as potential intermediaries of disease transmission from wildlife to humans among indigenous Waiwai in the Konashen Community Owned Conservation Area, Guyana. To address these objectives we 1) performed physical examinations and collected biological samples to assess Waiwai domestic dog health, and 2) administered questionnaires to characterize the role of dogs in the community and identify potential transmission pathways between wildlife, dogs, and humans. We observed ectoparasites on all dogs (n = 20), including: fleas (100%), ticks (15%), botflies (30%), and jigger flea lesions (Tunga penetrans) (80%). Ten percent of dogs were seropositive for Ehrlichia canis/ewingii, 10% were positive for Dirofilaria immitis, and one dog was seropositive for Leishmania infantum. All dogs (n = 20) were seronegative for: canine distemper virus, Brucella canis, Leptospira serovars, Trypanosoma cruzi, Anaplasma phagocytophilum/platys and Borrelia burgdorferi. Our questionnaire data revealed that the Waiwai remove ectoparasites from their dogs, clean up dog feces, and administer traditional and/or Western medicine to their dogs. White blood cell, strongyle-type ova, and eosinophil counts were lower in dogs that were not frequently used for hunting, dogs that did receive traditional and/or western medicine, and dogs that were frequently kept in elevated dog houses, although differences were not statistically significant. While our results suggest that the Waiwai have developed cultural practices that may promote dog health and/or prevent zoonotic disease transmission, more research is necessary to determine the efficacy of these practices. Our study provides important data on the health of dogs and the potential for disease transmission to humans in a zoonotic hotspot.

Domestic dogs are found throughout the world and interact closely with both wildlife and humans. Dogs can harbor numerous diseases that can be transmitted to other domestic and wildlife species, and human populations. They can serve as bridges, moving diseases between unconnected populations. Additionally, dogs can help in the early detection of wildlife and human diseases. Therefore, understanding what pathogens domestic dogs harbor can inform both wildlife and human health. In this study, we performed physical examinations, collected biological samples, and administered questionnaires to assess dog health and understand the role of dogs as potential bridges of disease transmission from wildlife to humans among indigenous Waiwai in the Konashen Community Owned Conservation Area, Guyana. On physical exam, we observed ectoparasites on all dogs, however, few pathogens were detected with diagnostic screening. Our questionnaire data revealed that the Waiwai engage in husbandry practices that may promote Waiwai dog health.

Visceral leishmaniasis in a recent transmission region: 27.4% infectivity rate among seronegative dogs

American visceral leishmaniasis (VL) is a parasitic disease whose main domestic reservoir in the urban environment is dog and is considered one of the most important zoonoses in the context of public health. Serological tests are typically used for the diagnostic screening of the disease. This study aimed to analyse the performance of different methodologies used in the diagnosis of VL in dogs sampled from a recent transmission area. The sample consisted of 52 dogs separated into groups based on the absence and presence of clinical signs of VL. The following serological techniques were carried out: the DPP® rapid test (RT), the ALERE® RT and an RT and immunoenzymatic assay with a recently developed protein (rKDDR-plus). In addition, molecular techniques were carried out with conjunctival swabs, and bone marrow aspirate samples and parasitological samples were obtained directly from bone marrow aspirates. It was concluded that 27.4% of seronegative dogs were infected, but the serological tests, used as screening tests, showed unsatisfactory sensitivity results (average: 51.2%) for dogs without clinical signs. It was suggested that polymerase chain reaction with conjunctival swabbing be used as a screening test for dogs without clinical signs, as this is a non-invasive collection technique with high-sensitivity values.

Leishmaniosis in a cat with chronic diarrhea as the only clinical manifestation

A 10‐year‐old male domestic shorthaired cat was presented with chronic diarrhea unresponsive to treatment. Laboratory testing identified hyperglobulinemia and mild nonregenerative anemia, and nongastrointestinal causes of diarrhea were ruled out. Gastrointestinal endoscopy and biopsy were performed and disclosed diffuse generalized granulomatous and lymphoplasmocytic inflammatory reaction in all segments of gastrointestinal tract evaluated, with numerous Leishmania spp. amastigotes within the cytoplasm of macrophages. The organism also was detected in spleen and bone marrow and Leishmania spp. serology was positive (immunofluorescence assay 1 : 160). A diagnosis of granulomatous enteritis secondary to leishmaniosis was made. Gastrointestinal signs resolved after treatment with allopurinol and a dietary supplement of nucleotides and active hexose‐correlated compounds (N‐AHCC), but seropositivity and gammopathy persisted 8 months later. The cat died of unrelated causes after an additional 3 months and permission for necropsy was not granted. Leishmaniosis as a cause of chronic diarrhea has not been reported previously in cats and should be considered in endemic areas in cats with chronic gastrointestinal signs.

Comparative Study of Real-Time PCR (TaqMan Probe and Sybr Green), Serological Techniques (ELISA, IFA and DAT) and Clinical Signs Evaluation, for the Diagnosis of Canine Leishmaniasis in Experimentally Infected Dogs

Canine leishmaniasis (CanL) diagnosis is not fully resolved. Currently, two specific methodologies are in continuous development, the detection of the parasite DNA or RNA in target organs and the detection of specific antibodies against Leishmania sp. For a correct diagnosis, it has been shown that the joint use of this type of test is necessary. In this work, a Sybr Green and a TaqMan Probe based on real time PCRs (qPCR) was performed for the detection of Leishmania sp. in order to correlate the results with clinicopathological and serological evaluations (IFA, ELISA and DAT) to propose an optimal biological sample to be used to detect the parasite in both early and late stages of the infection. A total of four samples were processed: conjunctival swabs, popliteal lymph node aspirates, bone marrow aspirates, and peripheral blood from experimentally infected dogs belonging to a larger study. Our results indicated that a single non-invasive sample (conjunctival swab) and the application of both types of qPCR would be reliable for determining Leishmania infection as well as the disease stage in dogs, thus avoiding bone marrow, lymph node aspirate or blood samples collection.

Nutritional Modulation of the Immune Response Mediated by Nucleotides in Canine Leishmaniosis

Leishmaniasis is an emerging, uncontrolled, and neglected zoonotic disease. Climate change is contributing to its ongoing global expansion. The dog is the main reservoir; hence the importance of implementing effective treatment, prevention, and control measures in this animal species to protect public health. However, although the standard treatment for canine leishmaniosis (CanL) is effective, it does not provide full parasitological clearance, and side effects and drug resistance have been described. The host's immune system plays a key role in the establishment and evolution of leishmaniasis. Dietary nucleotides modulate the immune response and, given their reported efficacy and safety in sick and clinically healthy Leishmania-infected dogs and because they represent a sustainable option with no associated side effects or resistance, they could be included within the prevention, treatment, and control strategies for leishmaniasis. This article briefly summarizes the scientific literature on CanL management, including unresolved issues, and reviews the scientific evidence on immunomodulatory effects of dietary nucleotides in different animal species. It also proposes a CanL management algorithm, including nucleotides. It is concluded that nutritional modulation of the immune response with nucleotides can contribute to better management of leishmaniasis following a One Health approach, especially in the COVID-19 era.

Antigens and their diagnostic performance for Canine Visceral Leishmaniasis: A critical review

Canine visceral leishmaniasis (CVL) is the most aggressive and lethal form of leishmaniasis manifesting in dogs and represents a major public health concern. Although there are sufficiently sensitive molecular tools for CVL diagnosis, they are not accessible at the main points of disease dissemination, in which context serodiagnosis has been used as an alternative tool on the epidemiological control. As an attempt to develop more accurate immunodiagnostic assays, many antigens have been tested over the years, on different platforms. This review aimed to access studies reporting new antigens that can be applied for CVL serodiagnosis. Articles published from January of 2016 to March of 2021 were retrieved from Google Scholar, Science Direct, and PubMed, using "Canine Visceral Leishmaniasis" and "Serodiagnosis" as keywords. In total, 1527 articles were identified, of which 42 were selected based on exclusion factors. Sensitivity, specificity, sample size, and sample quality data were extracted by manual curation and analyzed. Of the selected articles, 26 contemplated ELISA, which enabled a more thorough comparison and a critical review of these studies. Soluble Leishmania Antigens (SLA) and the A2 protein were used as controls in 53.8 and 46.15 % of these articles, respectively, and were evaluated separately; their frequent use was questioned. Subsequently, articles that evaluated other assay platforms, such as immunochromatography, immunosensors, and others, were also reported and evaluated. Finally, data relative to validation studies of commercial kits were briefly discussed. Our results show that there are several antigens with great potential for the development of accurate diagnostic tools, but further testing is required. The critical analysis also brings insights that can be useful for more assertive diagnostic development of more robust tools for CVL serodiagnosis.

Canine leishmaniosis in Tunisia: Growing prevalence, larger zones of infection

Background

Discovered by Nicolle and Comte in 1908 in Tunisia, Leishmania infantum is an intracellular protozoan responsible for zoonotic canine leishmaniosis (CanL) and zoonotic human visceral leishmaniasis (HVL). It is endemic in several regions of the world, including Tunisia, with dogs considered as the main domestic reservoir. The geographic expansion of canine leishmaniosis (CanL) has been linked to global environmental changes that have affected the density and the distribution of its sand fly vectors.

Methodology/Principal findings

In this study, a cross-sectional epidemiological survey on CanL was carried out in 8 localities in 8 bioclimatic areas of Tunisia. Blood samples were taken from 317 dogs after clinical examination. Collected sera were tested by indirect fluorescent antibody test (IFAT; 1:80) for the presence of anti-Leishmania infantum antibodies. The overall seroprevalence was 58.3% (185/317). Among positive dogs, only 16.7% showed clinical signs suggestive of leishmaniosis. Seroprevalence rates varied from 6.8% to 84.6% and from 28% to 66% by bioclimatic zone and age group, respectively. Serological positivity was not statistically associated with gender. The presence of Leishmania DNA in blood, using PCR, revealed 21.2% (64/302) prevalence in dogs, which varied by bioclimatic zone (7.3% to 31%) and age group (7% to 25%). The entomological survey carried out in the studied localities showed 16 species of the two genera (Phlebotomus and Sergentomyia). P. perniciosus, P. papatasi, and P. perfiliewi were the most dominant species with relative abundances of 34.7%, 25% and 20.4%, respectively.

Conclusions/Significance

The present report suggests a significant increase of CanL in all bioclimatic areas in Tunisia and confirms the ongoing spread of the infection of dogs to the country’s arid zone. Such an expansion of infection in dog population could be attributed to ecological, agronomic, social and climatic factors that affect the presence and density of the phlebotomine vectors.

Visceral leishmaniasis caused by Leishmania infantum is an endemic disease in several regions of the world, especially, in the Mediterranean basin, where dogs constitute the main domestic reservoir for humans. This zoonotic vector-borne disease is closely associated with the environment.

We carried out studies in 8 different regions of Tunisia, collecting and testing blood samples from 317 dogs. Out of which, more than half (58.3%) tested positive for L. infantum (IFAT+), although, only one-third of these displayed clinical signs. However, the detection of Leishmania DNA by blood PCR revealed a global prevalence in dogs of 21.2% (64/302) with a variation between bioclimatic zones. Our entomological survey revealed 16 sand fly species, dominated by the Phlebotomus and Sergentomyia genera, of which the most dominant were P. perniciosus, P. perfiliewi and P. papatasi. The first two of these are recognized vectors of L. infantum. Canine leishmaniosis continues to spread across Tunisia, moving southward, to arid zones because of global warming and agronomic and social factors affecting the presence and density of the phlebotomine vectors.

First Findings and Molecular Data of Phlebotomus mascittii (Diptera: Psychodidae) in the Cantabrian Cornice (Northern Spain)

Phlebotomus (Transphlebotomus) mascittii Grassi, 1908 (Diptera: Psychodidae) has been found in several European countries. In Spain, sporadic records were reported in the early '80s in Catalonia (Northeast Spain), and it was never detected again. Recent entomological surveys carried out between 2004 and 2020 revealed the presence of several specimens of P. mascittii in Spain. The species identification was confirmed by both morphological and molecular analyses. The analyzed specimens belonged to the haplotype (COI_2) defined by one polymorphic site compared to other European specimens. Phlebotomus mascittii was found in low population densities in rural areas associated with livestock farms and in an urban cemetery during the summer season. This study provides the first records of this species in various localities along the Cantabrian cornice (Northern Spain) and represents its westernmost observation in the Palearctic region. The implications of the finding of this uncommon species are discussed at different levels, with emphasis on its suspected role in the transmission of leishmaniosis.

Is the Prevalence of Leishmania infantum Linked to Breeds in Dogs? Characterization of Seropositive Dogs in Ibiza

Simple Summary

Leishmaniosis is an important zoonotic protozoan disease. Leishmania infantum is a protozoan species that accounts for the majority of cases in the Mediterranean. In this study, we analyzed the prevalence of infection in different dog breeds from Ibizan Island. Our results showed that the Doberman Pinscher and Boxer breeds present a higher prevalence of infection, and the relationship between antibodies’ serum titer and staging of disease was confirmed. Differences between age and sex were not found.

Abstract

Leishmaniosis is an important zoonotic protozoan disease primarily spread to the Mediterranean region by Leishmania infantum, the predominant protozoan species, which accounts for the majority of cases. Development of disease depends on the immune response of the definitive host and, predictably, their genetic background. Recent studies have revealed breed-typical haplotypes that are susceptible to the spread of the protozoan parasite. The objective of this study was to analyze the prevalence of leishmaniosis on a Mediterranean island and determine the relationship between disease prevalence and breed. In addition, information on seropositive animals was recorded to characterize animals affected by the disease. To study the prevalence, a total of 3141 dogs were analyzed. Of these, the 149 infected animals were examined for age, sex, antibody titer, and disease stage. We observed a prevalence of 4.74%, which varied between breeds (p < 0.05). The Doberman Pinscher and Boxer breeds had the highest prevalence of leishmaniosis. Significant differences were observed between breeds with common ancestors, emphasizing the important genetic component. Finally, regarding the characterization of seropositive animals, the distribution is similar to other studies. We discovered a relationship (p < 0.05) between the number of antibody titers and the clinical disease stage, which was also present in Leishmania infantum, suggesting that the development of the disease depends on the humoral or Th2 immune response with ineffective antibodies.

Canine Leishmaniosis in Greece: An Updated Countrywide Serological Study and Associated Risk Factors

Canine leishmaniosis (Leishmania infantum) is a zoonotic disease that affects dogs worldwide. Greece is enzootic for this disease, and updated data for its current distribution are of major importance. The aim of this cross-sectional serological study was primarily to update the current knowledge of Leishmania infantum seropositivity status within the asymptomatic Greek canine population and, furthermore, to assess the possible climatological and other risk factors. In total, sera of 1265 asymptomatic dogs were collected from all prefectures of the country. A questionnaire that included all individual dog information was completed for all animals. The Speed Leish K^® canine Leishmania antibody test kit (BVT Groupe Virbac, France) was employed. Potential risk factors were evaluated utilizing logistic regression models. Overall, 13.8% (n = 175) of the sampled dogs were seropositive to Leishmania infantum originating from all geographical departments of the country, whereas most prefectures had at least one seropositive animal. Outdoor living, high mean humidity, low mean wind speed and high total annual rainfall were found to increase the seropositivity status against the parasite. Conclusively, Leishmania infantum remains a common parasite challenge in the asymptomatic canine population of Greece, and therefore, its early diagnosis and effective prevention are significant in the country.

Prevalence and risk factors of Toxoplasma gondii and Leishmania spp. infections in apparently healthy dogs in west Shewa zone, Oromia, Ethiopia

BACKGROUND

In urban settings, the presence of a high density of the human population and contact with domestic and/or stray animals such as dogs and cats can be risk factors for the transmission of zoonotic protozoa parasites. Toxoplasma gondii (T. gondii) and Leishmania spp. are zoonotic protozoon parasites with significant health burdens worldwide.

METHODS

A cross-sectional study was used to investigate the antibody prevalence and risk factors of T. gondii and Leishmania spp. infections in 385 randomly selected dogs of Ambo, Bako, and Gojo towns of West Shewa Zone, Oromia regional state, Ethiopia. A questionnaire survey was administered to households to collect data on potential risk factors. Dog sera samples were assayed for T. gondii IgG antibodies using the direct agglutination test while Leishmania spp. specific antibodies tested using an indirect enzyme-linked immunosorbent assay (ELISA). Logistic regression was used for data analysis.

RESULTS

Overall, T. gondii and Leishmania spp. infection seroprevalence was found to be 82.86% (95% confidence interval (CI): 78.71-86.49%) and 92.47% (95% CI: 89.36-94.90%), respectively. Seropositivity for both T. gondii and Leishmania spp. was found in 82.58% of the dogs. None of the investigated factors were associated with Leishmania spp. seropositivity (p > 0.05). The seroprevalence of T. gondii was significantly different among the study towns (p = 0.003). The risk of T. gondii infection was 2.71 times higher in adult dogs than juvenile dogs (p = 0.043). Dogs kept simultaneously with other domestic animals had increased odds of T. gondii seropositivity compared to those with no other domestic animals (Adjusted Odds ratio: 1.96, p = 0.021). However, altitude, sex, breed, housing, feeding, educational level of head of the household, and dog's living area were not significantly associated with T. gondii seropositivity (p > 0.05).

CONCLUSIONS

The high seropositivity and the simultaneous presence of antibodies of T. gondii and Leishmania spp. in dogs suggest the widespread nature of these parasites in the environment and the high potential of transmission to other animals and humans. Further epidemiological studies, isolation and molecular characterization of the parasites, and educational campaigns are suggested.

Polymerase chain reaction using conjunctival swab samples for detecting Leishmania DNA in dogs

The dog is the main domestic reservoir of Leishmania and font of infection for the vector, constituting an important host for the transmission of the parasite to humans. Non-invasive collection of swab samples for leishmaniasis diagnosis has been a promising alternative. This study analyzed the positivity of polymerase chain reaction (PCR) for the diagnosis of canine leishmaniasis in conjunctiva samples. DNA extraction was performed using SDS 20% and PCR was performed using 13A/13B primers that amplify 120-bp of Leishmania kDNA. Of the 77 dogs analyzed, 50 (64.93%) had ocular changes: 25 (32.47%) dogs had periocular lesion, 41 (53.25%) dogs had purulent eye discharge, and 17 (22.08%) dogs had both signals. PCR was positive in 35 dogs (45.45%), and there was no significant difference between dogs with and without ocular signals (p=0.4074). PCR positivity was significant higher in dogs without periocular injury (p=0.0018). Conjunctive PCR, a less invasive, fast, and painless collection technique, is indicated to complement the diagnosis, especially in dogs without periocular injury, independent of the presence of purulent eye discharge.

Importation of Ticks on Companion Animals and the Risk of Spread of Tick-Borne Diseases to Non-Endemic Regions in Europe

Increased human mobility elevates the risk of exposure of companion animals travelling with their owners or imported from other regions to tick attacks. In this study, we highlight the potential role of dogs and cats taken for tourist trips or imported animals in the spread of ticks and tick-borne pathogens. The Rhipicephalus sanguineus tick, which is a vector of numerous pathogens causing diseases in animals and humans, is imported most frequently from endemic areas to many European countries. Additionally, alien tick species with high epizootic and epidemiological importance can be imported on dogs from other continents. Companion animals play an even greater role in the spread of autochthonous tick species and transmission of tick pathogens to other animals and humans. Although the veterinary and medical effects of the parasitism of ticks carried by companion animals travelling with owners or imported animals are poorly assessed, these animals seem to play a role in the rapid spread of tick-borne diseases. Development of strategies for protection of the health of companion animals in different geographic regions should take into account the potential emergence of unknown animal tick-borne diseases that can be transmitted by imported ticks.

Potential of Artesunate in the treatment of visceral leishmaniasis in dogs naturally infected by Leishmania infantum: Efficacy evidence from a randomized field trial

Leishmaniasis is among the world’s most neglected diseases. Dogs are the main reservoirs/hosts of Leishmania infantum, causative agent of both canine and human visceral leishmaniosis. Canine leishmaniasis (CanL) represents a public health problem as one of the most prevalent zoonotic diseases worldwide. Current therapeutics present drawbacks; thus, there is a need for more effective, safer, and cheaper drugs. The aim of this study was to evaluate and to compare the efficacy of oral administration of artesunate or meglumine antimoniate/allopurinol in dogs with clinical leishmaniasis. Forty-two dogs with naturally occurring clinical leishmaniasis were included in this open-label, simple randomized positive-control clinical field trial with 6 months of follow-up. Dogs received meglumine antimoniate 100 mg/kg/day and allopurinol 30 mg/kg/day for 28 days (control group, n = 26) or artesunate 25 mg/kg/day for 6 days (test group, n = 16). The animals were evaluated for their clinical evolution, parasite load (by qPCR) and humoral response at different time points: 0, 30, 90, and 180 days after treatment. Data analyses showed a significant improvement in both groups in clinical scores, parasitemia and antibody titers after treatment. Compared to the control group, the artesunate group showed significantly lower clinical score (P = 0.0001), lower parasitemia (P = 0.0001) and antibody titers after 6 months of follow-up. Compared to baseline values, a rapid, significant reduction (P < 0.012) in antibody levels, 2.28- versus 3.04-fold for the control versus artesunate groups, respectively, was observed 30 days after treatment. Antibody levels continued to decrease further in the artesunate group, where 58% of cases became seronegative at the 6-month follow-up. All qPCR-positive dogs were negative after treatment with artesunate, while 14.3% remained positive with the appearance of two new cases in the control group. Artesunate was well tolerated, and no side effects were recorded. Treatment failures were similar in both groups with 27.27% (6/22), including 18.18% (4/22) mortality in the control group, versus 26.66% (4/15), including 13.33% (2/15) mortality in the artesunate group. This is the first report showing the potential of artesunate in the treatment of dogs with clinical leishmaniasis. Artesunate showed higher efficacy than the current first-line treatment for CanL without any adverse effects. It could be a good alternative chemotherapy for CanL, and may be considered for further studies in human leishmaniases. Further clinical trials are needed to confirm these findings, to determine if there are relapses after treatment and if dogs remain infective to sandflies, to define the ideal therapeutic dosage and duration of treatment with artesunate.

Canine leishmaniasis (CanL) is a fatal, zoonotic vector-borne disease caused by Leishmania infantum, a common pathogen for both humans and dogs. Most CanL therapeutics are toxic, expensive, or ineffective. Artemisinin and derivatives have recently demonstrated potent antileishmanial activity in vitro and in experimental models. In this study, dogs with clinical leishmaniasis were randomly included in one of the treatment groups: meglumine antimoniate/allopurinol (control) or artesunate (alternative). Dogs were followed up for 6 months for their clinical score, parasitemia and Leishmania antibody levels. Both groups showed improved clinical scores, parasitemia and antibody titers after treatment. After six months of follow-up, treatment success was very similar in both groups, and 72.73% (16/22) of the controls versus 73.34% (11/15) in the artesunate group had clinical improvement. All dogs initially seropositive by PCR became negative after artesunate treatment, while 14.3% remained positive with the appearance of new cases in the control group. Antibody titers decreased rapidly (from day 30) from baseline especially in the artesunate group, where 58% of the dogs converted to seronegative after 6 months. Artesunate could be a good alternative for treatment of leishmaniasis. Additional clinical trials are needed to obtain more data on this drug.

Detection of Leishmania infantum DNA by real-time PCR in saliva of dogs

This study developed a real-time quantitative PCR (qPCR) assay to detect L. infantum kinetoplast DNA (kDNA) in canine saliva. The qPCR showed an efficiency of 93.8%, a coefficient of correlation of 0.996 and a detection limit of 0.5 fg/reaction (0.005 parasites), although it detected until 0.25 fg/reaction (0.0025 parasites). When samples from 12 dogs experimentally infected with L. infantum were collected, L. infantum kDNA was detected at 16-weeks post-infection (wpi) in 41.7% and 91.7% of saliva and bone marrow samples, respectively, and at 47-wpi in 75% of both samples. L. infantum kDNA can be detected by qPCR in canine saliva, with lower sensitivity in the early stages of infection and a lower parasite load estimation compared to bone marrow. However, saliva had similar sensitivities to bone marrow in the later stages of the infection and could be used to detect L. infantum kDNA being aware of its limitations.

Detection of Leishmania infantum DNA and antibodies against Anaplasma spp., Borrelia burgdorferi s.l. and Ehrlichia canis in a dog kennel in South-Central Romania

Canine vector-borne diseases are caused by pathogens transmitted by arthropods including ticks, mosquitoes and sand flies. Many canine vector-borne diseases are of zoonotic importance. This study aimed to assess the prevalence of vector-borne infections caused by Dirofilaria immitis, Ehrlichia canis, Borrelia burgdorferi sensu lato, Anaplasma spp. and Leishmania infantum in a dog kennel in Argeș County, Romania. Dog kennels are shelters for stray dogs with no officially registered owners that are gathered to be neutered and/or boarded for national/international adoptions by various public or private organizations. The international dog adoptions might represent a risk in the transmission of pathogens into new regions. In this context, a total number of 149 blood samples and 149 conjunctival swabs from asymptomatic kennel dogs were assessed using serology and quantitative real-time polymerase chain reaction. Antibodies against B. burgdorferi s.l. were detected in one dog (0.6%), anti-Anaplasma antibodies were found in five dogs (3.3%), while ten dogs (6.7%) tested positive for D. immitis antigen. Overall, 20.1% (30/149) of dogs were positive for L. infantum DNA. All samples were seronegative for anti-Leishmania antibodies. When adopting dogs from this region of Romania, owners should be aware of possible infection with especially L. infantum. The travel of infected dogs may introduce the infection to areas where leishmaniasis is not present.

Exploring the relationship between susceptibility to canine leishmaniosis and anti-Phlebotomus perniciosus saliva antibodies in Ibizan hounds and dogs of other breeds in Mallorca, Spain

Background

Canine leishmaniosis caused by Leishmania infantum is a neglected zoonosis transmitted by sand flies like Phlebotomus perniciosus. Clinical signs and disease susceptibility vary according to various factors, including host immune response and breed. In particular, Ibizan hounds appear more resistant. This immunocompetence could be attributed to a more frequent exposure to uninfected sand flies, eliciting a stronger anti-sand fly saliva antibody response.

Methods

This study aimed to investigate the prevalence of anti-P. perniciosus saliva antibodies in Ibizan hounds and dogs of other breeds in the Leishmania-endemic area of Mallorca, Spain, and to correlate these antibody levels with clinical, immunological and parasitological parameters. Anti-sand fly saliva IgG was examined in 47 Ibizan hounds and 45 dogs of other breeds using three methods: P. perniciosus whole salivary gland homogenate (SGH) ELISA; recombinant protein rSP03B ELISA; and rSP03B rapid tests (RT). Additionally, diagnostic performance was evaluated between methods.

Results

Results indicate significantly higher anti-SGH antibodies (P = 0.0061) and a trend for more positive SGH ELISA and RT results in Ibizan hounds compared to other breeds. General linear model analysis also found breed to be a significant factor in SGH ELISA units and a marginally significant factor in RT result. Although infection rates were similar between groups, Ibizan hounds included significantly more IFN-γ producers (P = 0.0122) and papular dermatitis cases (P < 0.0001). Older age and L. infantum seropositivity were also considered significant factors in sand fly saliva antibody levels according to at least one test. Fair agreement was found between all three tests, with the highest value between SGH and rSP03B RT.

Conclusions

To our knowledge, this is the first study elaborating the relationship between anti-P. perniciosus saliva antibodies and extensive clinical data in dogs in an endemic area. Our results suggest that Ibizan hounds experience a higher frequency of exposure to sand flies and have a stronger cellular immune response to L. infantum infection than other breed dogs. Additional sampling is needed to confirm results, but anti-P. perniciosus saliva antibodies appear to negatively correlate with susceptibility to L. infantum infection and could possibly contribute to the resistance observed in Ibizan hounds.

Noninvasive Biological Samples to Detect and Diagnose Infections due to Trypanosomatidae Parasites: A Systematic Review and Meta-Analysis

Unicellular eukaryotes of the Trypanosomatidae family include human and animal pathogens that belong to the Trypanosoma and Leishmania genera. Diagnosis of the diseases they cause requires the sampling of body fluids (e.g., blood, lymph, peritoneal fluid, cerebrospinal fluid) or organ biopsies (e.g., bone marrow, spleen), which are mostly obtained through invasive methods. Body fluids or appendages can be alternatives to these invasive biopsies but appropriateness remains poorly studied. To further address this question, we perform a systematic review on clues evidencing the presence of parasites, genetic material, antibodies, and antigens in body secretions, appendages, or the organs or proximal tissues that produce these materials. Paper selection was based on searches in PubMed, Web of Science, WorldWideScience, SciELO, Embase, and Google. The information of each selected article (n = 333) was classified into different sections and data were extracted from 77 papers. The presence of Trypanosomatidae parasites has been tracked in most of organs or proximal tissues that produce body secretions or appendages, in naturally or experimentally infected hosts. The meta-analysis highlights the paucity of studies on human African trypanosomiasis and an absence on animal trypanosomiasis. Among the collected data high heterogeneity in terms of the I2 statistic (100%) is recorded. A high positivity is recorded for antibody and genetic material detection in urine of patients and dogs suffering leishmaniasis, and of antigens for leishmaniasis and Chagas disease. Data on conjunctival swabs can be analyzed with molecular methods solely for dogs suffering canine visceral leishmaniasis. Saliva and hair/bristles showed a pretty good positivity that support their potential to be used for leishmaniasis diagnosis. In conclusion, our study pinpoints significant gaps that need to be filled in order to properly address the interest of body secretion and hair or bristles for the diagnosis of infections caused by Leishmania and by other Trypanosomatidae parasites.

The impact of canine leishmaniosis vaccination with Canileish® in Leishmania infantum infection seroprevalence studies

Effective vaccines against Leishmania parasites are a goal for the scientific community working with both canine and human leishmaniosis. However, possible side effects of vaccination should also be considered and evaluated, preferably before vaccine licensing and marketing. One of these possible effects is the cross-reaction of vaccine-induced antibodies with standard serological tests for detection of Leishmania infantum infection. Longitudinal studies were performed on the type of humoral profile induced by Brazilian marketed canine leishmaniosis vaccines, but little is known regarding the European situation. In this study, an annual follow-up of 85 CaniLeish® vaccinated dogs and 83 non-vaccinated control dogs was performed. Blood samples were taken for all animals at pre-determined time points: before vaccination; immediately before each one of the two following vaccine doses (at 21 days intervals); and then one, four, six, nine and 12 months after finishing the vaccination course. All samples were tested by an in-house ELISA, using a whole promastigote antigen, for the presence of anti-L. infantum antibodies. Humoral response detectable by the used serological diagnostic method was significantly higher in the vaccine group when compared with the control group (p < 0.01) until one-month post-vaccination. Results show that CaniLeish® vaccine-induced antibodies cross-react with a commonly used serological test for diagnosis of L. infantum natural infection. Implications of this interference are discussed, with special emphasis on a possible negative impact on canine leishmaniosis surveillance studies.

Field study of the improved rapid sand fly exposure test in areas endemic for canine leishmaniasis

BACKGROUND

Canine leishmaniasis (CanL) is a severe chronic disease caused by Leishmania infantum and transmitted by sand flies of which the main vector in the Western part of the Mediterranean basin is Phlebotomus perniciosus. Previously, an immunochromatographic test (ICT) was proposed to allow rapid evaluation of dog exposure to P. perniciosus. In the present study, we optimized the prototype and evaluated the detection accuracy of the ICT in field conditions. Possible cross-reactions with other hematophagous arthropods were also assessed.

METHODOLOGY/PRINCIPAL FINDINGS

The ICT was optimized by expressing the rSP03B protein in a HEK293 cell line, which delivered an increased specificity (94.92%). The ICT showed an excellent reproducibility and inter-person reliability, and was optimized for use with whole canine blood which rendered an excellent degree of agreement with the use of serum. Field detectability of the ICT was assessed by screening 186 dogs from different CanL endemic areas with both the SGH-ELISA and the ICT, and 154 longitudinally sampled dogs only with the ICT. The ICT results corresponded to the SGH-ELISA for most areas, depending on the statistical measure used. Furthermore, the ICT was able to show a clear seasonal fluctuation in the proportion of bitten dogs. Finally, we excluded cross-reactions between non-vector species and confirmed favorable cross-reactions with other L. infantum vectors belonging to the subgenus Larroussius.

CONCLUSIONS/SIGNIFICANCE

We have successfully optimized the ICT, now also suitable to be used with whole canine blood. The test is able to reflect the seasonal fluctuation in dog exposure and showed a good detectability in a field population of naturally exposed dogs, particularly in areas with a high seroprevalence of bitten dogs. Furthermore, our study showed the existence of favorable cross-reactions with other sand fly vectors thereby expanding its use in the field.

Evaluation of the circadian rhythm of anti-Leishmania IgG2 and IgA antibodies in serum and saliva of dogs with clinical leishmaniosis

In this study, the circadian rhythm of IgG2 and IgA specific antibodies in serum and saliva samples of 6 dogs experimentally infected with Leishmania infantum was assessed. Sampling was performed at 8.00, 12.00, 16.00, 20.00, and 00.00 h on two consecutive days. Anti-Leishmania antibody levels in serum were expressed without any correction, whereas in saliva were shown in different ways: without any correction, adjusted by protein concentration and corrected by the salivary flow rate. No significant differences in anti-Leishmania IgG2 antibody levels in serum and saliva samples with or without correction were found. Significant differences were found when anti-Leishmania IgA levels were corrected by the salivary flow rate. In addition, a greater intra-individual variation of antibody levels was observed in saliva than in serum. However, this variation did not modify the serological status of the dogs. Therefore, it could be concluded that there is no circadian rhythm in serum and saliva samples and sampling can be performed at any time of the day.

One-year follow-up of anti-Leishmania antibody concentrations in serum and saliva from experimentally infected dogs

The quantification of anti-Leishmania antibodies in serum and saliva by a time-resolved immunofluorometric assay is useful for the diagnosis and treatment monitoring of dogs with clinical leishmaniasis. We compared the kinetics of anti-Leishmania IgG2 and IgA antibodies in serum and saliva from 11 Beagle dogs experimentally infected with Leishmania infantum. Most dogs showed detectable concentrations of anti-Leishmania IgG2 earlier in serum (between 3 and 4 months p.i.) than in saliva (between 4 and 6 months p.i.). Overall, a high correlation between concentrations of anti-Leishmania IgG2 in serum and saliva (r = 0.853; P < 0.0001) was observed. The quantification of anti-Leishmania IgA showed less diagnostic value than IgG2, since detectable amounts of IgA were not observed in the saliva of four dogs and in the serum of one dog. In addition, a very low correlation between anti-Leishmania IgA in serum and saliva (r = 0.289; P < 0.001) was observed. Our results indicate that the antibodies against L. infantum in saliva appear approximately 1 month later than in serum, and suggest that there is a threshold for the passing of immunoglobulins from serum to saliva in dogs. These facts should be taken into consideration for a proper interpretation of saliva assays for quantification of antibodies.

Molecular xenomonitoring and host identification of Leishmania sand fly vectors in a Mediterranean periurban wildlife park

The epidemiological cycle of zoonotic phlebotomine-borne Leishmania infantum is a complex system in which domestic animals and wildlife interact and participate in its maintenance and transmission. In this study, we combined entomological surveillance, xenomonitoring of L. infantum and identification of host feeding sources of engorged females to investigate the potential contribution of a periurban wildlife park to leishmaniosis in neighbouring residential areas. Overall, 7,309 sand flies were collected in 111 trap-days during the summers of 2016-2018 in an endemic area in south-east Spain. Five different sand fly species were captured, with Phlebotomus perniciosus, the main L. infantum vector in this region, representing the most common species. Sand fly distribution was spatially heterogeneous in terms of species, sexes and female physiological stage (unfed, gravid and engorged females) and related to host distribution and management, and environmental features. None of the 602 sand flies analysed for L. infantum infection by kinetoplast real-time PCR were positive. We used molecular tools to identify the vertebrate hosts of sand flies and identified 17 host species, mainly mammals. Human DNA was not identified in engorged sand flies. This study provides evidence that wildlife parks in south-east Spain are ideal grounds for sand fly vectors but do not necessarily increase L. infantum infection risk to humans and dogs living in surrounding residential areas. This is probably because vectors feed mostly on non-L. infantum competent hosts and this should be investigated for a better understanding of the contribution of wildlife parks to the local epidemiology of L. infantum.

A new highly sensitive immunoassay for the detection of adiponectin in serum and saliva of dogs and its application in obesity and canine leishmaniosis

Adiponectin is an adipokine that exerts insulin-sensitizing and antiinflammatory properties. The aim of this study was to develop and validate a new heterologous ultrasensitive assay based on amplified luminescent technology for adiponectin determination in serum and saliva of dogs. A complete analytical validation of the assay was made in these fluids, and also this assay was applied to quantify adiponectin in serum and saliva of obese and lean dogs and dogs with leishmaniosis. These conditions were selected because in obesity there is a controversy about how adiponectin concentrations change in dogs, and in case of canine leishmaniosis, although it is described a decrease in serum adiponectin, there are not studies about how adiponectin changes after treatment. A total of 11 dogs were used in the validation and 26 dogs with different body condition and 8 with canine leishmaniosis were used for the clinical evaluation of the new assay for adiponectin quantification in serum and saliva of dogs. The analytical evaluation showed that the developed method could measure adiponectin in serum and saliva of dogs with high repeatability and sensitivity, adding a limit of quantification lower than commercially available ELISAs. In addition, significantly higher adiponectin concentrations were found in lean dogs and a correlation between serum and saliva was observed (P < .01). Moreover, dogs with leishmania presented reduced levels of adiponectin in serum. In conclusion, a new assay has been developed for adiponectin measurements which is more sensitive and faster than the traditional ELISA assays requiring less sample volume.

Evaluation of methods for detection of asymptomatic individuals infected with Leishmania infantum in the state of Piauí, Brazil

BACKGROUND

Visceral Leishmaniasis in humans presents with fever, anemia, and splenomegaly and can be lethal if not treated. Nevertheless, the majority of Leishmania infantum-infected individuals does not manifest symptoms and remain so provided they are not immunosuppressed. In this work, the performance of different tests was evaluated to detect asymptomatic individuals who were living in Teresina, Piauí state, Brazil, an endemic area for VL.

METHODOLOGY

L. infantum-specific antibodies were detected by ELISA and two different rapid immunochromatographic (IC) diagnostic tests, Kalazar Detect and OnSite, and parasitic loads were detected by real time PCR [qPCR]. Additionally, we measured levels of the biomarkers monokine induced by IFN-γ (MIG) and IFN-γ-induced protein 10 (IP-10) before and after stimulation of whole blood with soluble Leishmania antigen [SLA].

PRINCIPAL FINDINGS

Kalazar Detect and OnSite detected, respectively, 76% and 64% of patients presenting with active Visceral Leishmaniasis; 50% and 57% of patients remained positive in these tests, respectively, after treatment. Of the healthy participants in the study who were living in the endemic area, only 1.7% were positive with both of the IC tests. On the other hand, reactivity in ELISA tests revealed that 13% of these individuals presented asymptomatic infections; among VL patients, 84% presenting with active disease were reactive in ELISA, and after treatment, 55.5% were seropositive. L. infantum DNA was present in the blood of 37.9% of infected individuals living in the endemic area, while IP-10 and MIG biomarkers were detected in 26.7% of them. The greatest concordance of positivity occurred between ELISA and qPCR.

CONCLUSION

The association of different techniques can detect asymptomatic infections, however, more research is necessary to develop ideal biomarkers that are simple to use in the clinic and in field studies in areas endemic for Visceral Leishmaniasis.

Assessment of Vaccine-Induced Immunity Against Canine Visceral Leishmaniasis

Canine visceral leishmaniasis is an increasingly important public health problem. Dogs infected by Leishmania infantum are the main domestic reservoir of the parasite and play a key role in its transmission to humans. Recent findings have helped in the development of novel diagnostic methods, and of control measures such as vaccines, some of which are already commercially available. However, quantitative procedures should be followed to confirm whether these vaccines elicit a cell-mediated immune response. The present work describes the need for this evaluation, and the techniques available for confirming this type of immune response.

Risk of establishment of canine leishmaniasis infection through the import of dogs into South Africa

Canine leishmaniasis is a vector-borne disease caused by protozoa of the genus Leishmania that affect dogs, humans and wildlife. Sandflies of the genera Phlebotomus and Lutzomyia are the primary vectors. Canine leishmaniasis is an exotic and controlled disease in South Africa. The main purpose of our risk assessment study was to evaluate the likelihood that this exotic disease could enter and be established in South Africa through importation of live dogs. Risk analysis to the spread of the disease follows the World Organization for Animal Health (OIE) formal method of quantitative risk assessment documented as a step-by-step process. We have identified and discussed 11 possible risk factors involved in three steps for final assessment. The annual average number of diagnostic tests performed on imported dogs from 44 countries for 2011-2015 was 1158. Leishmania is reported to occur in 21/44 (47.7%) exporting countries. A total of 71.1% of Leishmania positive dogs were imported from these endemic countries. The yearly percentage of Leishmania positive dogs ranged from 0.2% to 2%. Three confirmed clinical and fatal cases of leishmaniasis in dogs of unidentified origin have been reported by our laboratory and the state veterinarians. The disease has been reported in neighbouring countries as well as the putative sandfly vectors. This study concluded that the risk for the introduction and degree of uncertainty of Leishmania in imported dogs in South Africa are moderate. Risk mitigation and recommendations such as investigations into possible occurrence of autochthonous leishmaniasis in the country, surveillance in its wildlife reservoirs and systematic surveillance of sandfly populations are discussed.

Canine visceral leishmaniasis: Detection of Leishmania spp. genome in peripheral blood of seropositive dogs by real-time polymerase chain reaction (rt-PCR)

Visceral leishmaniasis (VL) is a zoonosis caused by the protozoa of the genus Leishmania. Among the species, L. infantum and/or L. infantum (chagasi) are the most important species affecting the Americas. Domestic dogs are the main reservoir of the parasite and participate effectively in the parasite' transmission cycle. The Canine Visceral Leishmaniasis Control Program (PCLV) adopted in Brazil present as strategies the vector control, health education and serological diagnosis of CVL in dogs followed by culling of the seropositive ones. The resolution to eliminate seropositive dogs by euthanasia, when necessary, are the most controversial and least accepted by society. The diagnostic methods for canine visceral leishmaniasis, currently indicated and approved in Brazil by the Ministry of Health from Brazil are the Dual Path Platform (DPP)^® as a screening test and the Enzyme immunoassay test (ELISA^®). This study aimed to verify the presence of Leishmania spp. DNA in peripheral blood samples of dogs presenting positive serological results byDPP^® and ELISA^® tests,throughreal-time polymerase chain reaction (rt-PCR), using the pair of primers 150-152 already described. For this purpose, were collected blood samples from 185 seropositive dogs among them, 41 (22%) exhibited some clinical signal of disease, whereas 144 (78%) was asymptomatic. The animals were also analyzed according to gender, race and hair size. According to the results of rt-PCR, it was observed that among the185 seropositive dogs analyzed, only 132 (71%) presented positive results for CVL and 53 (29%) presented negative results. From this, 41/41 symptomatic dogs were positive (100%), while among the asymptomatic dogs, 91/144 were positive (63, 2%) and 53/144 were negative (36, 8%). Concerning the hair size of seropositive dogs, we found that 41 (22%) had long hair, while 144 (78%) had short hair. No statistical significance occurred between the results of rt-PCR, ELISA and DPP tests and the profile of the animals (gender, size of the dogs and hair size), probably due to the small number of samples and the sampling differences of each profile. But statistical significance occurred between the results of rt-PCR and the clinical evaluation, since the rt-PCR was positive in all symptomatic dogs. Thus, through these results, we reached at the following question, which may contribute to an important current debate: the dogs presenting CVL seropositive diagnosis confirmed by tests distributed by the Ministry of Health were in reality ill or were they seropositive by living in an endemic area of the disease? Would these asymptomatic seropositive dogs spread the disease to the inhabitants even presenting a low parasite charge circulating in the blood.

Seroprevalence of canine Leishmania infantum infection in the Mediterranean region and identification of risk factors: The example of North-Eastern and Pyrenean areas of Spain

The Mediterranean basin is an endemic region for canine leishmaniosis (CanL), where it represents a major veterinary problem and raises human health concerns. However, the distribution of the disease is heterogeneous and not all countries and locations have been equally studied and characterized. This work describes the situation of CanL in Girona province (Catalonia, Spain), for which no data has been previously reported, and presents a relevant study to exemplify other areas with similar characteristics across the region. Four cross-sectional seroprevalence surveys were performed from 2012 to 2016 throughout the province, including 36 sampling stations in 26 localities and a total of 593 dogs. For each animal, individual and location variables were also collected. Additionally, each dog owner answered a questionnaire about their knowledge of CanL and preventive methods used. Blood samples were analysed by an in-house ELISA and a mixed logistic regression model was used to assess the relationship between pre-determined variables and dog seropositivity. A Spearman's correlation was used to assess the association between dog owners' perceived risk of CanL and Leishmania infantum seropositivity in dogs at a given location. The overall true seroprevalence estimated for Girona province was 19.5% (95%CI: 15.5-23.5), of which only 6.8% (10/146) were considered symptomatic. Age of the dog [OR = 1.21 (95%CI: 1.11-1.31); p < 0.001] and altitude [OR = 0.02 (95%CI: 0.001-0.19); p = 0.001] were identified as risk factors for the infection. The results obtained in this study are expected to aid in the implementation of directed control programmes in CanL endemic areas throughout Europe, as well as to provide suitable data for the design of better risk assessment maps of the disease.

Antibodies and Molecular Detection of Leishmania (Leishmania) infantum in Samples of Free-Ranging Marmosets (Primates: Callitrichidae: Callithrix spp.) in an Area of Canine Visceral Leishmaniasis in Southeastern Brazil

Leishmaniasis is a vector-borne parasitic protozoan infection that affects mammals and involves a complex epidemiology. Although dogs are considered the main reservoir in zoonotic visceral leishmaniasis (VL), the possible presence of other mammalian species acting as reservoirs has been associated as a possible cause of lack of success in the control of human VL in many endemic areas. The knowledge about natural infections of some species is still scarce, such as nonhuman primates (NHP), especially from the genus Callithrix (marmosets). We investigated the infection by Leishmania (Leishmania) infantum, the agent of VL in the Americas, in 26 marmosets captured monthly, from April 2014 to March 2015, in an environmentally protected area (EPA) in Southeastern Brazil. The EPA has undergone significant environmental changes and has a transmission focus of canine VL since 2009. Serology was performed through the direct agglutination test, which detected low antibody titers in seven marmosets (7/26; 26.9%, 95% confidence interval 9.9-44.0), being five Callithrix penicillata (black-tufted-ear marmoset) and two Callithrix jacchus (white-tufted-ear marmoset). The presence of the DNA of Leishmania was investigated in blood and skin samples by PCR and genetic sequencing. This is the first report of the detection of L. (L.) infantum in the skin of a marmoset, which was verified in a sample from one C. penicillata. The results demonstrate the natural infection of marmosets by L. (L.) infantum and may suggest the participation of these animals as hosts in the parasite's transmission cycle in the EPA. However, more comprehensive studies are needed to elucidate their role on the VL epidemiology in this area and also in different endemic areas, especially because these NHP are increasingly in contact with humans and domestic animals, particularly due to environmental changes.